Spark-producing arrangement for a lighter with a battery

ABSTRACT

A spark-producing circuit arrangement having a source of D.C. voltage, an oscillating portion including a spark gap in the operating region of the flame and sensing the presence of the flame for turning off the oscillating portion when a flame is present.

United States Patent Cobarg 1 June 10, 1975 SPARK-PRODUCING ARRANGEMENTFOR [56] References Cited A LIGHTER WITH A BATTERY UNITED STATES PATENTS[75] Inventor: Claus Christian Cobarg, Steinbach, 3,045,148 7/1962McNulty et a1. 315/183 Germany 3,338,288 8/1967 3,488,131 1 1970 M t l.317 79 Assigneei Bran" Akfiengesellschafl, Kronberg, 3,589,848 6/1971431/78 Taunus, Germany 3,681,001 1/1972 Potts 432/264 [22] Filed: Sept.6, 1973 I Primary ExammerVolodymyr Y. Mayewsky 1 1 PP 394,749 Attorney,Agent, or Firm--Ernest F. Marmorek [30] Foreign Application PriorityData [57] ABSTRACT Sept. 6, Germany A park producing circuit arrangementhaving a source of DC. voltage, an oscillating portion including U-S- apark gap in the operating region of the flame and Cl. ensing thepresence of the flame for turning off the Fleld 0f Seal'clL. 3 CD,scillating portion when a flame is present 1 Claim, 7 Drawing FiguresSPARK-PRODUCING ARRANGEMENT FOR A LIGHTER WITH A BATTERY FIELD OFINVENTION The present invention relates to a spark-producing deviceemploying a battery for use especially in lighters having voltagetransducers capable of oscillations for producing a high voltage sparkand including a cut-in an'd cut-out switch which is operable by theoperating member of the spark-producing device itself so as to throw thevoltage transducer into and out of the circuit.

BACKGROUND OF THE INVENTION Spark-producing arrangements employingbatteries are already known in which a storage capacitor is charged updirectly from the battery and is discharged through a high voltageignition transformer by operating an actuating contact. Such anarrangement has a disadvantage in that the ignition transformer musthave a very high transformer ratio and a multi-cell battery isnecessary. For such reasons a spark-producing device of the above kindis relatively bulky.

Another spark-producing device employing a battery became known whichhas a voltage transducer capable of oscillations and through which astorage capacitor is charged to a voltage which is several times higherthan the battery voltage itself. After charging up the capacitor, thestorage capacitor becomes discharged through an ignition transformerafter a switch becomes operated. As is evident from the above, anadditional transformer is necessary for the oscillating part of thevoltage transducer. However, the last mentioned arrangement operateswith a single cell battery and its ignition transformer requires arelatively small transformer ratio and, therefore, its volume can bekept relatively small. The disadvantage of the above-mentionedsparkproducing arrangement resides in that it remains in operation foras long as the operating switch of the lighter is closed, even afterignition has taken place. In the case of pocket lighters, such repeatedand superfluous ignition will lead to a quick exhaustion of the battery.

SUMMARY OF THE INVENTION It is, therefore, an object of the presentinvention to provide an improved spark-producing arrangement employing abattery which does not have the abovementioned disadvantages of knownspark-producing devices and which is capable of increasing thereby theoperating life of the battery.

According to the present invention, a flame sensing means is providedwithin the spark-producing arrangement which controls a cut-out memberof the ignition device.

According to the present invention, a sparkproducing arrangementemploying a battery and having a transistorized voltage transdusingarrangement therein, the cut-out member is preferably provided in thefeedback path of the voltage transducer and located in the base circuitof the transducer.

According to the present invention it is preferred that the flamesensing means forms the cut-out member itself.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will become more readilyapparent from the following description of preferred embodiments thereofshown in the accompanying drawing, in which:

FIG. 1 illustrates the circuit connections of a sparkproducing deviceemploying a battery according to the present invention; and

FIGS. 2a-f illustrate various flame sensing devices which can be used inconnection with this sparkproducing arrangement according to the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to the circuitdiagram of FIG. 1, it is seen that it includes a battery 1, whichpreferably has a voltage of 1.5 volts, and an electrolyte capacitor 2,which is connected parallel to the battery 1. The fact that such a typeof capacitor is used has the advantage that even when the battery hasbeen relatively fully discharged, the spark-producing arrangement of thepresent invention will still be capable of proper functioning. Thecircuit diagram further includes a npn-type transistor 5, whichobviously can also be a pnp-type and, in the latter case, it is requiredonly to change the voltage polarities. The emitter of the transistor 5is connected to the negative terminal of the battery 1, while thecollector is connected over the primary winding 6 of an oscillationtransformer 9, with the make-contact of an operating switch 10, theother contact point of which is returned to the positive terminal of thebattery 1.

The oscillating transformer 9 further includes a feedback winding 7 aswell as a secondary winding 8. The feedback winding 7 is connected withone end thereof to the base of the transistor 5 and with the other endthereof to a tap-joint of a voltage divider circuit feeding the base ofthe transistor 5 and comprising the resistors 3 and 4. One end of thevoltage divider circuitis connected to ground, namely. at one end of theresistor 4,

whiile the other end of the voltage divider circuit is connected to themake-contact side of switch 10 at the end of resistor 3.

The secondary winding 8 of the oscillating transformer 9 has aVillard-type rectifier arrangement coupled thereto which includes astorage capacitor 11, diodes 12 and 13 and another storage capacitor 14.

Throughthe storage capacitor 14, the primary winding 15 of a highvoltage ignition transformer 17 is connected through a series circuit,including a thyristor 18.

The secondary side 16 of the high voltage ignition transformer 17 is incircuit connection with a spark gap 21.

According to the present invention, a flame-sensitive sensing means isprovided which controls a cut-out switch member of the ignitionarrangement. For this purpose the resistor 3 in the voltage dividercircuit feeding the base of transistor 5 is replaced by a switch memberwhich is placed in the operating range of the burning flame whichincludes a resistive part, the resistance of which increases withincreasing flame temperature. Such switching members are illustrated inFIGS. 2a and 2d and which, for example, can be a resistor with a PTCresistance characteristic (PTC=positive temperature co-efficient) or asillustrated in FIG. 2d, a birnetall switch which can be arranged to be anormally closed contact. Instead of the above arrangement, one mayreplace the resistor 4 in the circuit diagram of FIG. 1 by a switchingmember which has a resistance characteristic decreasing with increasingtemperature. Such switching member is illustrated in FIGS. 20 and 2b inalternatives and one is known as NTC-type resistors (NTC=negativetemperature co-efficient) the other operative as a bimetall switch asillustrated in FIG. 2b arranged as a normally open contact.

Another embodiment possible for sensing the flame temperature and toacting as a cut-out switch is when the resistor 4 is replaced by aninfrared sensor, such as, by an infra-red sensitive photo-resistor. Thistype of arrangement is illustrated in FIG. 2e.

Also, as a further possibility, one may place, near the ignited flame, aso-called ionization gap 22, illustrated in FIG. 2f, which can be in theform of a pair of wire tips placed at a small distance with respect toeach other. Such an ionization gap could then be used to replace theresistor 4. It is, however, assumed and required that the resistor 3always has a value which is considerably larger than the resistance ofthe ionization gap 22. The resistance of the gap 22 at an operatingflame lies between I and 20 M ohms. It is also noted that that, for thegenerally illustrated transistor 5, it is preferred to use a FET-typetransistor which requires a very slight base current.

Instead of replacing resistor 4 directly by the ionization gap 22, onemay arrange the gap 22 in such a manner that the gap 22 controls aswitching member such as an FET transistor which lies parallel with theresistor 4.

In each of the above-described cases, the circuit of the oscillatingarrangement must be designed in such a manner that when the operatingswitch is closed, then the oscillation will start. The above requirementcan be obtained by the appropriate dimensioning of the switchingelements, especially by appropriately selecting the bias voltage for thebase of the transistor 5, the winding ratio of the primary winding 6 andthe feedback winding 7.

The circuit arrangement illustrated in FIG. I operates as follows:

When the operating switch 10 is closed, a current will flow through thevoltage divider circuit consisting of resistors 3, 4. Consequently, abase current flows through the transistor 5 and through the return orfeedback winding 7 of transformer 9. As a result, there will also be acollector current flowing through the primary winding 6 and, due to thefact that there is an inductive effect between the windings oftransformer 9, and such effect is being fed-back through the feedbackwinding 7, the base voltage will increase further. Such a process willcontinue until the collector current reaches its maximum. Then, themagnetic flux density cannot increase anymore in the oscillatingtransformer 9 and the feedback winding 7 will not have any furtherinduced voltage therein, therefore, the transistor 5 will become turnedoff.

Due to the increase of the collector current, until the maximum value ofit is attained, there will be induced a voltage in the secondary winding8 which, through diode 12, will charge the storage capacitor 11 to atleast a partial value.

When the transistor 5 is turned off, as abovementioned, then in thesecondary winding 8 there will be an oppositely poled induced voltagepresent which will add to the voltage on the storage capacitor 11 andthrough diode 13, will charge up the storage capacitor 14. When there isno further charging current flowing into the storage capacitor 14, thenthe diode 13 will block and the energy stored in the winding capacity ofthe secondary winding 8 of transformer 9 will discharge itself throughthe oscillating transformer 9 and will induce a voltage in the feedbackwinding 7 of the transformer 9, which voltage will turn on again thetransistor 5 and will thereby introduce a new oscillating cycle. Itfollows from the above that the oscillated portion includes elements3-9, while the charging circuit includes elements 11-14.

The above described charging and discharging cycles repeat themselvesuntil the storage capacitor 14 will carry a charge corresponding to thebreakdown voltage of the thyristor 18. At such instant, the storagecapacitor 14 will discharge through the high voltage ignitiontransformer 17 whereupon there is a spark produced across the spark gap21.

The circuit diagram illustrated in FIG. 1 is designed in such a mannerthat the oscillations will continue after the storage capacitor 14 hasdischarged and the above described oscillating process keeps repeatingitself.

According to a preferred embodiment of the present invention, thevoltage transducer or oscillator will turn itself off only when the gasor whatever fuel is used is already burning. For this purpose, theresistor 3, as above described, can be made as a PTC resistor which isplaced in the operating range of the flame. Due to the heat produced bythe flame, the resistance of the PTC resistor 3 will increase itselfconsiderably within a short period of time so that the bias voltage ofthe transistor base will be reduced to a value which is too small foranother cycle of oscillation. It is assumed that the oscillating stateof the voltage transducer or oscillator portion is relatively difficultto upset by changing the bias voltage of the transistor base. However,it is relatively easy to prevent a starting of the oscillation directlyafter the storage capacitor 14 has been discharged just by changing thebias voltage on the base of transistor As already has been mentionedabove, instead of the PTC resistor 3, one may use a bimetall switchillustrated in FIG. 2d. In such a case, as soon as the flame starts toburn, the bimetall switch of FIG. 2d becomes heated and will open up sothat the base of transistor 5 will become grounded through the resistor4 and the further oscillations of the transducer or oscillator portionis prevented.

In the event that in the switching arrangement of FIG. 1 the resistor isa NTC resistor. as illustrated in FIG. 2c, then the resistance value ofsuch a reistor will decrease considerably through the exposure to theheat of the flame and thereby the bias voltage to the base of transistor5 will be reduced with the consequence, as mentioned above in connectionwith the PTC resistor, namely the oscillation will stop.

A similar effect will be attained when the NTC resistor 4 is replaced bya normally open bimetall switch, such as illustrated in FIG. 2b, whichwill become closed under the effect ot the heat of the flame.

The resistor 4 can be replaced by an infra-red sensitive photo-resistoras illustrated in FIG. 22. Such a photo-resistor reduces its resistancevalue when radiation hits it, so that it will have a similar effect aswhen a NTC resistor is used.

In the event that an ionization gap 22 is used as the flame sensor, thetips of the electrodes of which are exposed to the immediate region ofthe flame, but outside the spark gap 21, then using such an ionizationgap 22 instead of the resistor 4 will have the same effect as the use ofan NTC resistor.

The switching arrangement illustrated in FIG. 1 can be modified severalways. For example, a self-cleaning or wiping contactor can be used,which, after having been operated once allows the sparking to go on onlyfor a certain number of times before the switch can be operated again.As a result, an excessive use of the battery is avoided and this isespecially advantageous in the event other operating deffects arepresent or when the fuel tank is empty.

I wish it to be understood that I do not desire to be limited to theexact details of construction shown and described, for obviousmodifications will occur to a person skilled in the art.

Having thus described the invention, what I claim as new and desire tobe secured by Letters Patent, is as follows:

1. A spark-producing circuit comprising a source of DC. voltage, anoscillating means including spark means coupled to said course of DC.voltage, a sensing means placed adjacent said flame and sensing thepresence of the flame for turning off said oscillating means when aflame is present, said oscillating means comprises a voltage transducermeans having a primary, a

secondary and a feedback winding, a transistor device having a baseelectrode connected to said feedback winding, a primary windingconnected to said collector electrode, a voltage dividing circuitincluding said sensor means connected through said feedback winding tothe base electrode of said transistor device, an operating switch meansconnecting said voltage divider circuit to one terminal of said DC.voltage source, a discharge circuit connected to said secondary windingand including a storage capacitor means and a thyristor device connectedin a series therewith and capable of producing a high voltage pulse whenthe charge in said storage capacitor attains a predetermined breakdownvoltage of said thyristor means, a high voltage step-up transformermeans having a primary winding connected in series with said storagecapacitor means and said thyristor means and a secondary winding, aspark gap means connected in series with said secondary winding of saidstep-up transformer means, whereby a spark is produced in said spark gapmeans when said storage capacitor discharges over said thyristor device.l l

1. A spark-producing circuit comprising a source of D.C. voltage, anoscillating means including spark means coupled to said course of D.C.voltage, a sensing means placed adjacent said flame and sensing thepresence of the flame for turning off said oscillating means when aflame is present, said oscillating means comprises a voltage transducermeans having a primary, a secondary and a feedback winding, a transistordevice having a base electrode connected to said feedback winding, aprimary winding connected to said collector electrode, a voltagedividing circuit including said sensor means connected through saidfeedback winding to the base electrode of said transistor device, anoperating switch means connecting said voltage divider circuit to oneterminal of said D.C. voltage source, a discharge circuit connected tosaid secondary winding and including a storage capacitor means and athyristor device connected in a series therewith and capable ofproducing a high voltage pulse when the charge in said storage capacitorattains a predetermined breakdown voltage of said thyristor means, ahigh voltage step-up transformer means having a primary windingconnected in series with said storage capacitor means and said thyristormeans and a secondary winding, a spark gap means connected in serieswith said secondary winding of said step-up transformer means, whereby aspark is produced in said spark gap means when said storage capacitordischarges over said thyristor device.